(http://curl.haxx.se/bug/view.cgi?id=2154627) which pointed out that libcurl
  uses strcasecmp() in multiple places where it causes failures when the
  Turkish locale is used. This is because 'i' and 'I' isn't the same letter so
  strcasecmp() on those letters are different in Turkish than in English (or
  just about all other languages). I thus introduced a totally new internal
  function in libcurl (called Curl_ascii_equal) for doing case insentive
  comparisons for english-(ascii?) style strings that thus will make "file"
  and "FILE" match even if the Turkish locale is selected.